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Fluids, Electrolytes
Wk 12 & 13 Ch 26
| Question | Answer |
|---|---|
| What are the three major buffer systems in the body? | bicarbonate, phosphate, and protein buffer systems |
| What accounts for two-thirds volume and is in the intracellular fluid (ICF) compartment? | Water |
| Where is one-third or so of body water found? | outside cells, in the extracellular fluid (ECF) compartment. |
| What is the major cation in ECF? What is the major cation in ICF? What are the intracellular anion counterparts of ECF’s chloride ions? | Na+ K+ HPO4 2– protein anions. |
| What accounts for about 90% of the mass of dissolved solutes in plasma, 60% in the IF, and 97% in the ICF? | Proteins and some of the nonelectrolytes (phospholipids, cholesterol, and triglycerides) |
| Water that vaporizes out of the lungs in expired air or diffuses directly through the skin is called what? | insensible water loss |
| What triggers thirst? | A rise in plasma osmolality |
| An increase in plasma osmolality of only 2–3% excites what? | the hypothalamic thirst center. |
| The hypothalamic thirst center neurons are stimulated when their osmoreceptors lose water by osmosis to the hypertonic ECF, or are activated by angiotensin II, by baroreceptor inputs, or other stimuli and collectively cause what? | the sensation of thirst |
| What senses the ECF solute concentration and trigger or inhibit ADH release from the posterior pituitary accordingly? | Osmoreceptors of the hypothalamus |
| A decrease in ECF osmolality does what which allows more water to be excreted in urine, restoring normal blood osmolality. | inhibits ADH release |
| an increase in ECF osmolality stimulates what by stimulating the hypothalamic osmoreceptors. | ADH release |
| What is decreased urine output called? | oliguria |
| What is a serious consequence of water loss from plasma is inadequate blood volume to maintain normal circulation? | hypovolemic shock |
| In the occurrence of dehydration, where is water lost from? | ECF |
| In a type of cellular overhydration called hypotonic hydration, the ECF is diluted—its sodium content is normal, but excess water is present. | True |
| What is the hallmark of the condition of hypotonic hydration? | hyponatremia |
| What is the condition of unusually low levels of plasma proteins, results in tissue edema because protein-deficient plasma has an abnormally low colloid osmotic pressure. | hypoproteinemia |
| Which salts account for 90–95% of all solutes in the ECF, and they contribute about 280 mOsm of the total ECF solute concentration (300 mOsm). | NaHCO3 and NaCl |
| At its normal plasma concentration of about 142 mEq/L, what is the single most abundant cation in the ECF and the only one exerting significant osmotic pressure. | Na+ |
| Does reabsorption of Na+ exhibit a transport maximum? | not it does not, and in healthy individuals nearly all Na+ in the urinary filtrate can be reabsorbed. |
| What has the greatest effect on renal regulation of sodium ion concentrations in the ECF? | the hormone aldosterone |
| What usually promotes both sodium and water retention? | aldosterone |
| Although urinary excretion of large amounts of Na+ always results in the excretion of large amounts of water as well, the reverse is true/not true? | not true |
| What is the most important trigger for aldosterone release from the adrenal cortex? | the renin-angiotensin mechanism mediated by the juxtaglomerular apparatus of the renal tubules |
| When the juxtaglomerular (JG) apparatus responds to (1) sympathetic stimulation, (2) decreased filtrate NaCl concentration, or (3) decreased stretch (due to decreased blood pressure), what is released from the granular cells? | they release renin which catalyzes the series of reactions that produce angiotensin II, which prompts aldosterone release. |
| What 2 things depress release of renin, angiotensin II, and aldosterone? | high renal blood pressure and high filtrate NaCl concentrations |
| As the glomerular filtration rate rises in response to baroreceptors, what increases? | Na+ output and water output increase. |
| What reduces blood pressure and blood volume by inhibiting nearly all events that promote vasoconstriction and Na+ and water retention? | Atrial Natriuretic Peptide (ANP) |
| What promotes excretion of Na+ and water by the kidneys by inhibiting the ability of the collecting duct to reabsorb Na+ and by suppressing the release of ADH, renin, and aldosterone? | Atrial Natriuretic Peptide (ANP) |
| What hormones are chemically similar to aldosterone and, like aldosterone, enhance NaCl reabsorption by the renal tubules? | estrogens |
| What appears to decrease Na+ reabsorption by blocking the effect aldosterone has on the renal tubules, thus, having a diuretic-like effect and promotes Na+ and water loss. | progesterone |
| What is part of the body’s buffer system, and resists changes in the pH of body fluids? | Potassium |
| The responsibility for K+ balance falls chiefly on what? | the cortical collecting ducts |
| Renal regulation of K+ is thru excretion. Because the kidneys have a limited ability to retain K+, it may be lost in urine even in the face of a deficiency. | True |
| What is the single most important factor influencing K+ secretion? | the K+ concentration in blood plasma |
| What is the second factor influencing K+ secretion into the filtrate? | aldosterone |
| Under the influence of aldosterone, as plasma Na+ levels rise, what levels fall proportionately? | K+ |
| What is the most important effect ionic calcium has in the ECF besides normal blood clotting, cell membrane permeability, and secretory behavior? | neuromuscular excitability |
| What increases excitability and causes muscle tetany? | Hypocalcemia |
| What is as dangerous as hypocalcemia because it inhibits neurons and muscle cells and may cause life-threatening cardiac arrhythmias? | Hypercalcemia |
| Declining plasma levels of Ca2+ directly stimulate the parathyroid glands to release PTH, which promotes an increase in calcium levels by targeting which 3 organs? | 1. Bones. 2. Small intestine. 3. Kidneys. |
| As a rule, 75% of the filtered phosphate ions (including H2PO4–, HPO42–, and PO43–) are reabsorbed in the PCT by active transport. Phosphate reabsorption is set by its transport maximum. | True |
| What is the major anion accompanying Na+ in the ECF and, like sodium, it helps maintain the osmotic pressure of the blood | Chloride |
| What happens when most other anions, such as sulfates and nitrates, reach their transport maximums, and their concentrations in the filtrate exceed the amount that can be reabsorbed? | excesses spill into urine. |
| Whenever the pH of arterial blood rises above 7.45, a person is said to have what? | alkalosis or alkalemia. |
| A drop in arterial pH to below 7.35 results in what? | acidosis or acidemia |
| A pH of 7.35 is not acidic but is a higher-than-optimal H+ concentration for most cells, so any arterial pH between 7.35 and 7.0 is called what? | physiological acidosis |
| breakdown of phosphorus-containing proteins releases what into the ECF? | phosphoric acid |
| anaerobic respiration of glucose produces what? | lactic acid |
| fat metabolism yields other organic acids, such as what? | fatty acids and ketone bodies |
| the loading and transport of carbon dioxide in the blood as HCO3– liberates what? | hydrogen ions |
| What is all the available HCO3– ions when acids enter the blood, often referred to as? | the alkaline reserve |
| net carbon dioxide retention (hypoventilation) leads to what? | acidosis, pH below 7.35 |
| hyperventilation, which causes net elimination of CO2, causes what? | alkalosis, pH above 7.45 |
| What are the two most important renal mechanisms for regulating acid-base balance of the blood? | (1) conserving (reabsorbing) or generating new HCO3–, and (2) excreting HCO3– |
| What occurs mainly in the PCT and in type A intercalated cells of the collecting duct? | Secretion of H+ |
| The two renal mechanisms commonly carried out by the type A intercalated cells of the collecting ducts generate new HCO3– are: | Excretion of Buffered H+; excretion of NH4+ |
| What is the most important urine buffer? | the phosphate buffer system, specifically its weak base monohydrogen phosphate (HPO42–). |
| What's the most common cause of acid-base imbalance, usually when a person breathes shallowly or gas exchange is hampered by diseases like pneumonia, cystic fibrosis, or emphysema | Respiratory acidosis |
| What results from hyperventilation (carbon dioxide is eliminated from the body faster than it is produced) | Respiratory alkalosis |
| What is the second most common cause of acid-base imbalance,and is recognized by low blood pH and HCO3– levels. | metabolic acidosis |
| What is indicated by rising blood pH and HCO3– levels, is much less common than metabolic acidosis. | Metabolic alkalosis |
| What are the absolute blood pH limits for life? | a low of 7.0 and a high of 7.8. |
| About how much body water is found within cells in the intracellular fluid (ICF) compartment; and how much is in the extracellular fluid (ECF) compartment. The ECF includes plasma and interstitial fluid. | two-thirds (25 L) one-third (15 L) |
| What are the most abundant ECF electrolytes? | sodium, chloride, and bicarbonate ions |
| Filtrate is forced out of the capillaries by ________ and pulled back in by ____________ | hydrostatic pressure colloid osmotic pressure |
| What triggers the thirst mechanism, and is mediated by what? | Increased plasma osmolality hypothalamic osmoreceptors |
| What is triggered if ECF osmolality is high, or if a large drop in blood volume or pressure occurs? | ADH release |
| A serious consequence of dehydration is what? | hypovolemic shock |
| What occurs when body fluids are excessively diluted and cells become swollen by water entry. The most serious consequence is cerebral edema. | Hypotonic hydration |
| What are the most abundant solutes in ECF. They exert the bulk of ECF osmotic pressure and control water volume and distribution in the body. | Sodium salts |
| What ion is transported by the renal tubule cells and helps regulate K+, Cl–, HCO3–, and H+ concentrations in the ECF? | Na+ |
| What promotes Na+ reabsorption and H2O conservation, unless other mechanisms favor water excretion? | Aldosterone |
| Declining blood pressure and falling filtrate osmolality stimulate the granular cells to release what which via angiotensin II, enhances systemic blood pressure and aldosterone release? | renin |
| What leads to vasodilation and enhanced Na+ and water loss in urine? | Rising arterial pressure |
| What promotes vasoconstriction and conserves Na+ and water? | Falling arterial pressure |
| What is released by certain atrial cells in response to rising blood pressure (or blood volume), causes systemic vasodilation and inhibits renin, aldosterone, and ADH release and enhances Na+ and water excretion, reducing blood volume and blood pressure? | Atrial natriuretic peptide (ANP) |
| What 2 substances increase renal retention of sodium? | Estrogens and glucocorticoids |
| When blood pH is normal or slightly high, what is the major anion accompanying sodium reabsorption. | chloride |
| In acidosis, what is replaced by bicarbonate. | chloride |
| What are generated by breakdown of phosphorus-containing proteins, incomplete oxidation of fats or glucose, and the loading and transport of carbon dioxide in the blood. | acids |
| What are the following: the bicarbonate, phosphate, and protein buffer systems. | Chemical buffers of the body |
| CO2 combines with H2O to form what? | carbonic acid. |
| buffers act by _______hydrogen ions when there is a rise in pH | releasing |
| Buffers act by ________hydrogen ions when there is a decrease in pH | binding |
| the respiratory system also acts to regulate the acid-base balance of the body and is known as what kind of buffering system? | a physiological buffering system. |
| What enzyme is present in erythrocytes and is responsible for the coercion of carbon dioxide into bicarbonate? | carbonic anhydrase |
| What medical condition increases respiration (hyperventilation) and elevates the blood pH? | Respiratory alkalosis |
| What medical condition decreases respiration (hypoventilation) and causes increased blood carbon dioxide and decreased pH? | Respiratory acidosis |
| What metabolic condition is the pH of the blood elevated beyond the normal range (7.35-7.45)? | Metabolic alkalosis |
| What process which if unchecked leads to acidemia, i.e. blood pH is low (less than 7.35) due to increased production of H+ by the body or the inability of the body to form bicarbonate (HCO3-) in the kidney | metabolic acidosis |
| What are the absolute high and low blood pH limits for life? | low of 7.0 and a high of 7.8. |
| What are the most abundant ECF electrolytes? | sodium, chloride, and bicarbonate ions. |
| What do intracellular fluids contain large amounts of? | protein anions and potassium, phosphate, and magnesium ions. |
| Filtrate is forced out of the capillaries by _______pressure and pulled back in by ________ _______ pressure. | hydrostatic colloid osmotic |
| What is the thirst mechanism, mediated by? | hypothalamic osmoreceptors |
| What results from carbon dioxide retention? | Respiratory acidosis |
| What occurs when carbon dioxide is eliminated faster than it is produced. | respiratory alkalosis |
| What occurs when fixed acids (lactic acid, ketone bodies, and others) accumulate in the blood or when bicarbonate is lost from the body? | Metabolic acidosis |
| What occurs when bicarbonate levels are excessive? | metabolic alkalosis |
| What are the 2 types of extracellular fluid (ECF)? | Interstitial-surrounds the cells plasma - fluid component of blood |
| What is the fluid found within the cells called and what is it aka? | intracellular fluid (ICF) aka cytosol |
| What % of body's fluids are intracellular? | 62% |
| What % of body's fluids is interstitial? | 30% |
| What % of body's fluids is plasma? | 8% |
| What are proteins considered when they are dispersed in body fluids? | colloids |
| Why are proteins considered to be electrolytes? | because they carry a negative charge |
| What are the major positive ions (cations) found dissolved in body fluids? | Na+, K+, Ca2+, Mg2+ |
| What are the major negative ions (anions)found dissolved in body fluids? | Cl-, HCO3- (bicarbonate), HPO4 2- and H2PO4- (both phosphate), SO2 4- (sulfate), organic acids and proteins |
| What is the major positive ion found in extracellular plasma fluid? major negative ion? | Na+; Cl- |
| What is the major positive ion found in intracellular fluid? major negative ion? | K+; protein and phosphates |
| What are some of the 7 major functions of electrolytes in the body? | serve as cofactors for enzymes- (cofactors act w/enzymes to speed up reactions) action potentials in neuron and muscle cells secretion and action in hormones and neurotransmitters muscle contraction acid/base balance secondary active transport osmos |
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svking01
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